These data and information are intended for science
researchers, students from elementary through
college, policy makers, and general public.

Supplemental_Information:

Equipment Used -
sidescansonar GLORIA long-range side-scan sonar
airgun 160 and 80 cu in single-channel seismic-reflection system
3dot5khz 3.5 khz bathymetry
10khz 10 khz bathymetry
magnetics
loranc Loran C
transitsatellite Satellite receiver
gps Global Positioning System
Notes -
LEG 1:
&nbsp;&nbsp;
Leg 1 focused on the western half of the Gulf of Mexico, seaward of
Texas and Louisiana, and abutting GLORIA coverage from a 1982 survey. This
portion of the Gulf is dominated by salt tectonics. The area mapped with
GLORIA during this leg was 45,000 sq nautical miles.
&nbsp;&nbsp;
Data Summary - Leg 1
&nbsp;&nbsp;
At sea a total of 27 days
&nbsp;&nbsp;
Mileage for each type of data collected:
&nbsp;&nbsp;
GLORIA sidescan 4430 nm 8195 km
&nbsp;&nbsp;
3.5 kHz 4594 nm 8504 km
&nbsp;&nbsp;
10 kHz 4594 nm 8504 km
&nbsp;&nbsp;
airgun 4430 nm 8195 km
&nbsp;&nbsp;
magnetometer 4080 nm 7548 km
&nbsp;&nbsp;
Comments - Leg 1:
&nbsp;&nbsp;
The weather during leg 1 was generally excellent except for two
hurricanes. Hurricane Danny resulted in a loss of 13 hours of operation
on August 14, 1985, and Hurricane Elena delayed arrival in New Orleans one
day, from September 2 to September 3, 1985.
&nbsp;&nbsp;
The impact that the warm surface water and strong thermocline
present in the Gulf of Mexico in the summer would have on the range of the
GLORIA system was not realized. Although GLORIA was run at a 30 sec.
repetition rate (45 km swath width) the maximum swath width actually obtained
was 8 km in approximately 1000 m of water. This required reducing the
trackline spacing, adding additional tracklines, and thus limiting the effort
in water depths shallower than 1000 m.
&nbsp;&nbsp;
Initially, much time was spent getting all equipment operational.
The GLORIA system suffered from logging problems resulting in a loss of
approximately 24 hours of data during the cruise. The longest continuous
down time period was 12 hours. Dirt particles in the air being pulled across
the recording heads by the air conditioning system appears to have been the
major problem. The airgun system was down a total of approximately 24 hours
due to compressor, streamer, and airgun problems. The longest continuous
period of down time was 7 hours. The magnetometer required 3 days to get
operational initially, but this was partly a result of its lowest priority.
A new computer system was installed for this cruise. Most of the leg was
required to get the system operating properly. Navigation had to be plotted
by hand for the duration of the cruise. Summary data plots for the cruise,
however, track line plots were completed with the computer system at the end
of the cruise.
&nbsp;&nbsp;
The data in the western Gulf are very interesting geologically. The
Sigsbee Escarpment can be identified on the sonographs with piles of debris
in places at its base. A continuous channel can be traced from the shelf edge
through the diapir province of the slope, forming a reentrant in the Sigsbee
Escarpment, and then meandering seaward across the rise into the deep
water of the Gulf. The fan of the Rio Grande has a braided channel system,
on which are features interpreted to be bedforms. Similar bedforms are
present seaward of the Sigsbee Escarpment suggesting that strong bottom
currents are present in the region.
Publications -
Paskevich, Valerie F.; Wong, Florence L.; O'Malley, John J.; Stevenson,
Andrew J.; Gutmacher, Christina E., 2010, GLORIA sidescan-sonar imagery
for parts of the U.S. Exclusive Economic Zone and adjacent areas: U.S.
Geological Survey Open-File Report 2010-1332,
<A HREF="<http://pubs.er.usgs.gov/publication/ofr20101332>"
target="OF1"><http://pubs.er.usgs.gov/publication/ofr20101332>.
&nbsp;&nbsp;
Twichell, David C., and Paskevich, Valerie, 1996, GLORIA sidescan sonar
field data and navigation data collected in the Gulf of Mexico during
R/V Farnella cruises in 1982 and 1985: U.S. Geological Survey Open-File
Report 96-707,
<A HREF="<http://woodshole.er.usgs.gov/publications/of96-707/OPR96_707/INTRO.HTM>"
target="OF2"><http://woodshole.er.usgs.gov/publications/of96-707/OPR96_707/INTRO.HTM>.

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Please recognize the U.S. Geological Survey (USGS) as
the source of this information.
Physical materials are under controlled on-site access.
Some USGS information accessed through this means
may be preliminary in nature and presented without
the approval of the Director of the USGS. This
information is provided with the understanding
that it is not guaranteed to be correct or complete
and conclusions drawn from such information are
the responsibility of the user.
This information is not intended for navigational
purposes.
Any use of trade, firm, or product names is for
descriptive purposes only and does not imply
endorsement by the U.S. Government.